binary examples

Author: benblack86

src/benblack86/binary/BasicBinary.java

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+package benblack86.binary;
+
+public class BasicBinary {
+	public static void main(String args[]) {
+
+		System.out.printf("Capacity of primitives:\n");
+		System.out.printf("  byte [ 8 bits]  min:%s max:%s\n", Byte.MIN_VALUE, Byte.MAX_VALUE);
+		System.out.printf(" short [16 bits] min:%s max:%s\n", Short.MIN_VALUE, Short.MAX_VALUE);
+		System.out.printf("   int [32 bits] min:%s max:%s\n", Integer.MIN_VALUE, Integer.MAX_VALUE);
+		System.out.printf("  long [64 bits] min:%s max:%s\n", Long.MIN_VALUE, Long.MAX_VALUE);
+
+		// 0x => hexadecimal (0xF => 15, 0x10 => 16)
+		// 0b => binary (0b11 => 3)
+		
+		// i >> x: shift bits in i right by x positions (2 >> 1 => 1)
+		// i << x: shift bits in i left by x positions (1 << 1 => 2)
+		
+		System.out.printf("\nPrint binary using method 1:\n");
+		for(int i = 125; i < 130; i++) {
+			printBinary(i);
+		}
+		printBinary(-100);
+		
+		System.out.printf("\nPrint binary using method 2:\n");
+		for(int i = 125; i < 130; i++) {
+			printBinary2(i);
+		}
+		printBinary2(-100);
+		
+		
+		System.out.printf("\nBinary operations:\n");
+		printBinary(128);     // 00000000000000000000000010000000 (128)
+		printBinary(~128);    // 11111111111111111111111101111111 (-129)
+		printBinary(-128);    // 11111111111111111111111110000000 (-128)
+		printBinary(~-128);   // 00000000000000000000000001111111 (127)
+		printBinary(128>>>1); // 00000000000000000000000001000000 (64) 
+		printBinary(128>>>2); // 00000000000000000000000000100000 (32)
+		printBinary(128>>1);  // 00000000000000000000000001000000 (64)
+		printBinary(128>>2);  // 00000000000000000000000000100000 (32)
+		printBinary(-127>>>1);// 01111111111111111111111111000000 (2147483584)
+		printBinary(-127>>>2);// 00111111111111111111111111100000 (1073741792)
+		printBinary(-127>>1); // 11111111111111111111111111000000 (-64)
+		printBinary(-127>>2); // 11111111111111111111111111100000 (-32)
+	}
+	
+	public static void printBinary(int i) {
+		System.out.printf("%12s: ", i);
+		for(int k = 31; k > -1; k--) {
+			// need abs to work with negative numbers
+			System.out.printf("%s", Math.abs(i >> k) % 2);
+		}
+		System.out.printf("\n");
+	}
+	
+	public static void printBinary2(int i) {
+		System.out.printf("%12s: ", i);
+		for(int k = 31; k > -1; k--) {
+			// shift bit to the most significant position and apply mask
+			System.out.printf("%s", i >> k & 0b1);
+		}
+		System.out.printf("\n");
+	}
+}

src/benblack86/binary/BitSetTest.java

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+package benblack86.binary;
+
+import java.util.BitSet;
+
+public class BitSetTest {
+	private static final int RUNS = 100000;
+	private static final int NUM_BITS = 64;
+	// every other bit set
+	private static long setMask = 0xAAAAAAAAAAAAAAAAl;
+
+	private static long nativeBitTest() {
+		long bits = 0;
+		int found = 0;
+		bits |= setMask;
+
+		long start = System.currentTimeMillis();
+
+		for (int bit = 0; bit < NUM_BITS; ++bit) {
+			if (((bits >>> bit) & 0b1) == 0) {
+				++found;
+			}
+		}
+		
+		System.out.printf("found: %s\n", found);
+
+		return System.currentTimeMillis() - start;
+	}
+
+	private static long bitsetBitTest() {
+		BitSet bits = new BitSet(NUM_BITS);
+		for (int bit = 1; bit < NUM_BITS; bit += 2) {
+			bits.set(bit);
+		}
+
+		long start = System.currentTimeMillis();
+
+		int found = 0;
+		for (int i = bits.nextClearBit(0); i < NUM_BITS; i = bits.nextClearBit(i + 1)) {
+			++found;
+		}
+		
+		System.out.printf("found: %s\n", found);
+
+		return System.currentTimeMillis() - start;
+	}
+
+	public static void main(String[] args) {
+		double totalNative, totalBitset = totalNative = 0;
+
+		for (double i = 0; i < RUNS; ++i) {
+			totalNative += nativeBitTest();
+			totalBitset += bitsetBitTest();
+		}
+
+		System.out.printf("Native: %f BitSet: %f", totalNative / RUNS, totalBitset / RUNS);
+	}
+}